1.05 Unit Test: Expressions and Problem Solving

Which equation represents this number sentence? Three less than one-fifth of a number is 28.

1/5n−3=28

Which expression represents the phrase "twice the difference of a number and 5"?

2(x−5)

Which equation represents this sentence? Five more than three times the number is one-third more than the sum of the number and itself.

3n+5=(n+n)+13

Demarco wrote two correct variable expressions to represent the phrase "the product of a number and 7". Which variable expressions could Demarco have written? Select each correct answer.

A. n⋅7 b. 7n

Ohm's Law is given by the equation V = IR where V is voltage in watts, I is current in amperes, and R is resistance in Ohms. A lamp needs 0.5 amperes. Which equation can be used to determine the voltage for a given amount of resistance?

V = 0.5R

Madelyn drove a race car in a race. She averaged 55 mph and began the race 0.5 hours ahead of the other drivers. The variable d represents Madelyn's distance driven, in miles. The variable t represents the number of hours since the other drivers began to race. Which equation can be used to determine the distance Madelyn drove t hours into the race?

d=55(t+0.5)

Which variable expression represents the phrase "the sum of a number and 10"?

n + 10

Which equation represents this number sentence? Nine more than the quotient of a number and 3 is 21.

n/3+9=21

Fuel wood is measured in cords. The number of cords in a pile l ft long, w ft wide, and h ft tall can be estimated using the equation number of cords=lwh/128. Orin measures a pile of wood to be 18 ft long by 24 ft wide. Which equation can be used to determine the number of cords in a pile of wood h ft tall?

number of cords=432h/128