If y = 3.5 when x = 0.7, then what is y when x = 0.4

Question

Having trouble understanding this

Answer 1

First find a when given y = 3.5 when x = 0.7,

y = ax

3.5 = a(0.7)

5 = a

Now we can use the equation y =5x and the the fact that x = 0.4 to find y:

y = 5x

y = 5 (0.4) = 2