This is a simultaneous equation question.answer and steps plz.

Number of 10 cent coins = 14

Number of 50 cent coins = 7

Step-by-step explanation:

Let the number of coins of 10 cents = a

and the number of coins of 50 cents = b

Total count of coins = 21

a + b = 21  (1)

Value of 10 cent coins = $0.10

Value of a coins of 10 cents = 0.10a

Value of 50 cent coins = $0.50

Value of b coins of 50 cents = 0.50a

The value of these coins = $4.90

0.10a + 0.50b = 4.90

a + 5b = 49 (2)

By subtracting equation (1) from equation (2)

(a + 5b) - (a + b) = 49 - 21

4b = 28

b = 7

From equation (1),

a + 7 = 21

a = 21 - 7

a = 14

Therefore, number of 10 cents coins = 14

number of 50 cent coins = 7

$1,320

Step-by-step explanation:

~Multiply to find how much money he made that week

55 * 30 = $1,650

~Multiply by 20% then subtract

1,650 * 0.2 = 330

1.650 - 330 = 1,320

Best of Luck!