Yup! We're all pretty good here. :)
Answer:
60
Step-by-step explanation:
Divide the number of questions answered correctly by his percentage
51 / 85 = 0.6
Now multiply that answer by 100 to see how many questions are on the quiz
0.6 x 100 = 60
Check your work by dividing that number by the number he answered correctly
51 / 60 = 0.85
<em>What you need to find is the extra amount of plywood. To do that, you must find the area of the square and the area of the circle and subtract them to find the answer.</em>
Formulas:
area of a square: A = bh
area of a circle: A =

square measurements:
b = 28
h = 28
circle measurements:

(≈3.14)
r = 14
A = (28)(28)
A = 784
area of square = 784 in^2
A = 3.14 (

)
A = 3.14 (196)
A = 615.44 in^2
784 - 615.44 = 168.56
The amount of plywood left over is 168.56 in^2.