Modeling With Expressions

5 less than a number is 15.

• x - 5 = 15
• 5 - x = 15
• 15 - x = 5

Two more than 4 times a number is -18.

• 4x + 2 = -18
• 2x + 4 = -18
• 18 = 4x +2

Twice a number is 24.

• 2n = 24
• 2/n = 24
• 2 + n = 24
• 2 - n = 24

What is the difference between an expression and equation?

• Expressions have an equal sign and equations do not have an equal sign
• Expressions do not have an equal sign and equations do have an equal sign
• There is not a difference
• Expressions do not have variables and equations have variables

A number tripled subtracted from 60 is the same as 21.

• 3c − 60 = 21
• 60 − 3 = 21c
• 60 − 3c = 21
• c(60 − 3) = 21

Eight less than three times a number is equivalent to thirty four.

• 3x - 8 = 34

• 8x - 3 = 34

• 8 - 3x = 34

• 8 - x = 34

Fifteen less than half a number is equivalent to eleven.

• (1/2)x + 15 = 11

• 2x - 15 = 11

• 15 - (1/2)x = 11

• (1/2)x - 15 = 11

Twelve more than three quarters of a number is equal to thirty six.

• 75x + 12 = 36

• (3/4)x + 12 = 36

• 3x + 12 = 36

• 25x + 12 = 36

One quarter the difference of a number and twenty eight is equal to nine.

• (1/4)x - 28 = 9

• (1/4)(x - 28) = 9

• 25x - 28 = 9

• (1/4)(x + 28) = 9

Twice the sum of four times and number and ten is equal to seventy two.

• 4x + 10 = 72

• 2(x + 10) = 72

• 2(4x + 10) = 72

• 8x + 10 = 72