Solve Mentally
a/8 = 7
a = 56
a + 3 = 8
a = 5
a - 5 = 4
a = 9
5a = 25
a = 5
a/7 = 9
a = 63
a - 8 = 18
a = 26
a + 8 = 12
a - 21 = 49
a = 70
25a = 625
a = 25
a/8 = 12
a = 96
a - 60 = 100
a = 160
a + 6 = 21
a = 15
a - 180 = 300
a = 480
18a = 486
a = 27
a/10 = 15
a = 150
a + 11 = 24
a = 13
a + 30 = 120
a = 90
a - 1,820 = 980
a = 2,800
108a = 2268
a = 21
a/8 = 13
a = 104
8a = 72
a = 9
A stunt airplane is flying at 150 feet. It ascends to 325 feet. Write and solve an addition equation to find the change in altitude of the airplane.
Equation: 150 + x = 325
Solution: x = 175
Virginia lost 12 marbles. She still has 24 marbles. Write and solve a subtraction equation to figure out how many marbles she had to start.
Solution: x = 36
Equation: 18 = 3x
Solution: x = 6
A bag of Super Dog dog food at $12.85 is one third the price of a bag of Power Dog dog food. Write and solve a division equation to find the price of Power Dog dog food.
Equation: 12.85 = x/3
Solution: x = 38.55