X = number of lessons, y = total cost
y = 15x + 20 <== ur equation
when total bill was 125...y = 125
125 = 15x + 20
125 - 20 = 15x
105 = 15x
105/15 = x
7 = x <=== if Bill took 7 lessons, it would cost 125 <==
One is an Integer. One is odd and is not prime.
You forgot to put a picture
Assuming that you ment- (18*9)/3d where d=3 you would follow PEMDAS-
Parentheses
Exponents
Multiplication-Division (in order from right to left)
Addition-Subtraction (in order from right to left)
1. Parentheses- (18*9)=162
2. Solve your variables- 3d (3*3)=9
Giving you- 162/9
3. Solve-162/9=18
Area of canvas= 113 square in
area of one side= 113/4=28.22
=28 square in