To describe the relationship between \( t \), the number of trees in the orchard, and \( a \), the number of apples harvested, assuming the relationship is proportional, we can start with the ratio of apples to trees.
Given that the apple picker harvested 84 apples from 3 trees, we can find the rate of apples per tree:
\[ \text{Rate} = \frac{84 \text{ apples}}{3 \text{ trees}} = 28 \text{ apples/tree} \]
This means for any number of trees \( t \), the total number of apples \( a \) can be expressed as:
\[ a = 28t \]
We can also express this equation in different terms by using the information given:
- From the equation \( a = 28t \), we can express \( a \) as a function of \( t \) directly.
- Rearranging it gives us \( t = \frac{a}{28} \).
Given the options provided, let's evaluate them:
- \( at=843 \) - This implies \( a = \frac{843}{t} \), which doesn't directly derive from the proportionality established. (Not a valid equation)
- \( \frac{A}{t} = \frac{84}{3} \) - This expresses the rate of apples per tree, which is equivalent to \( \frac{A}{t} = 28 \). This could also be valid depending on how \( A \) is understood to represent "apples harvested." (Valid representation of the rate)
- \( t = \frac{843}{a} \) - This would imply a different relationship; if \( a = 84 \) for 3 trees, (Not a valid equation)
- \( t = \frac{84}{a} \) - This implies that for apples, this would not express \( t \) correctly for proportional apples per tree. (Not a valid equation)
- \( at=84*3 \) - This equation would hold true since \( a \) is the total apples and \( t \) is the total trees; when substituting known values gives you the right number. (Valid equation since it represents total apples for all trees)
- \( a = \frac{843}{t} \) - Similar to other direct equations of the ratio, where assuming total products, can express meaningful bounds; if \( a = 84t \) based on trees. (Valid based on known quantities)
So the valid selections based on reasoning derived from the relationships of the quantities involved would be:
- \( \frac{A}{t} = \frac{84}{3} \) (valid rate equation)
- \( a t = 84 * 3 \) (valid total equation)
- \( a = \frac{843}{t} \) (interpretative valid equation but needs contextual backing)
Thus, those selections express meaningful attributes of the relationship directly reflecting the proportionality involved in the apple yield across trees.