Question

the weight of jacobs backpack is made up of the weight of the contents of the backpack as well as the weight of the backpack itself. seventy percent of the total weight is textbooks. his notebooks weigh a total of 4 pounds, the backpack itself weighs 2 pounds. if the backpack contains only textbooks and notebooks, which equation can be used to determine $t$, the weight of the textbooks?
$0.7(t) = t - 4 - 2$
$0.7(t) = t + 4 + 2$
$0.7t(4 + 2) = t$
$0.7(t + 4 + 2) = t$

Explanation:

Step1: Define total weight

Let total weight = $t + 4 + 2$, where $t$ = textbook weight, 4 = notebook weight, 2 = backpack weight.

Step2: Relate textbooks to total weight

70% of total weight equals textbook weight: $0.7 \times (\text{total weight}) = t$
Substitute total weight: $0.7(t + 4 + 2) = t$

Answer:

0.7(t + 4 + 2) = t