Question

Two numbers are in the ratio 7:9. The smaller number is 42 , what is the larger number?

Answer 1

42 = 7*6
so,
7:9 = 7*6 : 9*6 = 42:54

Answer 2

7/9 = 42/n.
7n = 378,
n = 54.

Answer 3

Or just 42 *(9/7)

Answer 4

You can do
42×9/7
x=6×9=54

Answer 5

Yes, that is also a valid method. It is using the fact that if two ratios are equivalent, then their corresponding values are also equivalent. So if we have 7:9 and we know the smaller number is 42, we can use the equivalent ratio 7x : 9x and solve for x, which gives us x=6. Then we can find the larger number by multiplying 9x = 9(6) = 54.