How to do this question plz answer me step by step plzz plz

adult cost £7, child cost £2

Step-by-step explanation:

let a represent an adult and c a child , then

2a + 3c = 20 → (1)

a + 4c = 15 → (2)

Multiplying (2) by - 2 and adding to (1) will eliminate a

- 2a - 8c = - 30 → (3)

Add (1) and (3) term by term to eliminate a, that is

- 5c = - 10 ( divide both sides by - 5 )

c = 2

Substitute c = 2 into either of the 2 equations and evaluate for a

Substituting into (2)

a + 4(2) = 15

a + 8 = 15 ( subtract 8 from both sides )

a = 7

The cost of an adult ticket is £7 and a child ticket is £2

assuming you mean addition: addition and subtraction are reverse operations.

step-by-step explanation:

step-by-step explanation:

circumference divided by 3.141592654 then timesthe radius twice