Note that a change can be an increase or a decrease. For an increase, use a positive number.
For a decrease, use a negative number.

(a) Laura pumped 7 gallons of water into her pool each minute for 14 minutes. What was the total change in the amount of water in the pool?

step-by-step explanation:

hans did not square the 40-unit side; he merely multiplied it by 2.   incorrect.

yes

step-by-step explanation:

so of course you want to start by plugging the 5 in which goes to 7(5)+3(5)=50 because 7*5=35 and 3*5=15 and then add them together, then plug in the 5 to the other equation as well 9(5)+5=50 because 9*5= 45 and then add 5 and so yes they are equivalent.