Question

the variables x and y vary inversely with a constant variation of 7. Use the variation formula, k=xy, to find why when x=9

Answer 1

1.Make y the subject

k = xy

k/x = xy/x

y = k/x

2.Substitute

y = k/x

y = 7/9

y = 0.777......

y = 0.8 (Answer)

To confirm

k = xy

k = 9 × 0.8

k = 7.2

k = 7 (constant)

Hope it helps☺