Answer:
50 nickels, 20 quarters.
Step-by-step explanation:
System of equations (q = # of quarters, n = # of nickels):
<em>q + n = 70, 0.25q + 0.05n = 7.50</em>
the first equation can be changed to q = 70 - n, so we are able to <em>substitute q with 70 - n</em>.
So, it will look like <em>0.25*70 - 0.25n + 0.05n = 7.50</em>. This can be simplified to <em>0.2n = 10</em>, which means that n = 50.
Knowing that we can solve <em>q + 50 = 70</em>, which means that q = 20.
Answer:
her first mistake was on line 3.
line 1: 80 + [2(3 1/2 + 1 1/2)]
line 2: 80 + [2(5)]
line 3: 80 + 10
line 4: 90
Step-by-step explanation:
on line 3 she added 80 + 2, but she should have multiplied 2 by 5. the correct steps would be:
line 1: 80 + [2(3 1/2 + 1 1/2)]
line 2: 80 + [2(5)]
line 3: 80 + 10
line 4: 90
