Question

X km/h = y mph

Use 8 km/h = 5 mph to write a formula for y in terms of x.

Can somebody explain this question to me without using a calculator?
Thank you.

Answer 1

y=(5/8)x

Explanation:

y/x=5/8

y=(5/8)x

Answer 2

Let's first write down the equations which we will require to solve for this problem.

Equation No. 1 -
x km/h = y mph

Equation No. 2 -
8 km/h = 5 mph

First of all, we will make y the subject by calculating the km/h when mph = 1. We will accomplish this by dividing both sides by 5 as displayed below:

Equation No. 2 -
8 km/h = 5 mph
5 mph = 8 km/h
5 / 5 mph = 8 / 5 km/h
1 mph = 8 / 5 km/h

Through this, we have found out:

m = 8 / 5

We will use the y = mx formula in order to obtain our final equation. We will substitute the value given in the second equation into the formula.

y = mx
y = ( 8 / 5 ) x