A belt and a wallet cost $42, while seven belts and four wallets cost $213.

A) how much do four belts and four wallets cost?

B) how much do three belts cost?

B + w = 42

7b+4w=213

-7b-7w=-294

7b+4w=213

-3w=-81

w=27

b + 27 = 42

b = 15

four belts total $60

four wallets total $108

three belts total $45

Let, the cost of a belt = x

cost of a wallet = y

Then, system of equations would be:

x + y = 42

7x + 4y = 213

Multiply 1st equation by 4,

4x + 4y = 168

Substitute it from 2nd equation,

3x = 45

x = 15

Now, substitute it in 1st equation,

15 + y = 42

y = 42 - 15 = 27

In short, Belt costs $15 and wallet costs $27

A)

15x4=60

27x4=108

60+108=

four belts and four wallets cost 168

B) 3x15=

three belts cost 45