Question

If x and 3.5y vary directly and x = 7 when y = 10 find x when y = 15



answer is 10.5 I know the answer please know me how to solve this question... irrevelant question will be reported​

Answer 1

Step-by-step explanation:

Let x = k × 3.5y

when x = 7, y = 10,

k × 3.5 × 10 = 7

k = 7 ÷ 10 ÷ 3.5 = 0.2

so k = 0.2

when y = 15,

x = 3.5 × 0.2 × 15 = 10.5

Answer 2

Answer:

by cross multiplication

x=7×15/10

x=105/10

x=10.5