Answer: he got 12 questions right
he got 20 questions wrong.
Step-by-step explanation:
Let x represent the number of questions that he got right.
Let y represent the number of questions that he got wrong.
His mother said she would pay him 10 cents for each right answer. This means that if he gets x questions right, he would earn $10x.
His mother said she would subtract 5 cents for each wrong answer. This means that if he gets y questions wrong, he would earn
- $5y.
If he solved 32 problems, it means that
x + y = 32
If he earned 20 cents after doing 32 problems,it means that
10x - 5y = 20 - - - - - - - - -1
Substituting x = 32 - y into equation 1, it becomes
10(32 - y) - 5y = 20
320 - 10y - 5y = 20
- 10y - 5y = 20 - 320
- 15y = - 300
y = - 300/ -15 = 20
Substituting y = 20 into x = 32 - y, it becomes.
x = 32 - 20 = 12
To get more than a dollar, he needs to earn at least 110 cents. He already has 20 cents. He needs to get 9 right to earn over a dollar.
If he gets 9 right, he would earn 90 cents more. 90 + 20 = 110 cents = $1.1
