Question

6

A girl has $2.85 in nickels and quarters. How many of each type of coin does she have if there

are 21 coins in all? *

(4 Points)

n + 9 = 21 and .05n + .25q = 2.85

n = 12,9 = 9

n = 5,9 = 26

n = 31, 9 = 22

n = 5,9 = 7

Answer 1

n = 12, q = 9

Explanation:

The simultaneous equation that represents the expression is;

n + q = 21 .......... 1

0.05n + 0.25q = 2.85 ........ 2

Multiply equation 2 by 100 to have;

5n + 25q = 285

n + 5q = 57

____________________________________

n + 5q = 57

n + q = 21

Substract the resulting equations

5q-q = 57-21

4q = 36

q = 36/4

q = 9

Substitute q = 9 into eqn 1;

From 1; n+q = 21

n = 21-q

n = 21-9

n = 12

Hence she has 12 nickels and 9 quarters