Question

r= -0.075t + 3.85 solve for t
r=3.7
-0.075t + 3.85 < 3.7
-0.075t + 3.85 - 3.85 <3.7 - 3.85 + 0.15
-0.075t/-0.075 > -0.185/-0.075

This is as far as I can get - now how do you solve for t?

Answer 1

so it's an inequality~ i think for the first equation you've written, you mean:
r > -0.075t + 3.85
because you've written
-0.075t + 3.85 < 3.7
(it's the same as r > -0.075t + 3.85 ; the left side just became the right side of the inequality and vice-versa)

you're on the right track actually,, :)
i think in -0.075t + 3.85 - 3.85 <3.7 - 3.85 + 0.15 ,, the plus sign (+) must be equal sign (=), so;
-0.075t + 3.85 - 3.85 < 0.15
-0.075t < 0.15
divide both sides by the numerical coefficient of t to get t alone (note: numerical coefficient is the number before the variable t ; in this case, it is -0.075) ,, therefore:
t < 0.15/(-0.075)
t < -2

thus t is any number less than 2, so it can be
1.7, 1, 0, -2.4, -5, etc.

hope this helps :)

Answer 2

wait, it should be
t > -2
*i forgot to tell that if you divide both sides by a negative number, the inequality sign becomes the opposite,, that's why (<) becomes (>)

and so please don't mind the
"thus t is any number less than 2, so it can be
1.7, 1, 0, -2.4, -5, etc. "
it's wrong,, sorry!

it should be:
thus t is any number GREATER THAN -2, so t can be:
-1, 0 , 2, 3.6, 5.4, 7, etc.

hope this helps~ :)

Answer 3

jai's answer is NOT correct

-0.075t + 3.85 < 3.7
Add -3.85 to both sides
-0.075t + 3.85 + -3.85 < 3.7 + -3.85
-0.075t < -0.15
Divide both sides by -0.075
When dividing by a negative the sense of the inequality reverses
t > 2