Question

Your teacher wants to see if you can guess your two quiz grades. She tells you that the second quiz grade is 21 points higher than the first quiz grade. She also tells you that twice the first quiz grade is 57 points more than the second quiz grade. What were your two quiz grades?

Answer 1

78 and 99

Explanation:

Answer 2

78 and 99

Explanation:

let x be the first quiz grade and y be the second quiz grade. we can set up this formula:

x+21 = y

and this formula:

2x-57 = y

therefore, x+21 = 2x-57

add 57 to both sides: x+78 = 2x

subtract x from both sides: 78 = 2x-x

simplify: 78 = x

now we know the first quiz grade is 78. we can plug this into the first formula:

78+21 = y

add to get y = 99