Question

Make a the subject of the formula:
4b(5a-2) =2c

Answer 1

`a = (2)/(5) + (c)/(10b)`

Explanation:

Expand 4b(5a-2) on the left side

4b(5a-2) = 4b · 5a -4b · (-2)

= 20ab -8b

Therefore we get

20ab -8b = 2c

Add 8b on both sides to get rid of the -8b on the left

20ab - 8b + 8b = 2c + 8b

20ab = 8b + 2c

Divide by 20 both sides:
20ab/20 = 8b/20 + 2c/20

ab = (2/5)b + c/10

Divide by b both sides

==> ab/b = (2/5)b/b + c/10b

==> a = 2/5 + c/10b

Answer 2

Explanation:

Firstly you have to open brackets

4b(5a - 2) = 2c

20ab - 8b = 2c

20ab = 2c + 8b

Divide both sides by 20b(coefficient of a)

a = (2c + 8b)/20b