He seemed to be warming up

d

explanation:

the following key ideas correctly express the key sentence.

restate key idea: most people can learn to swim in ten short lessons.

restate key idea: the majority of water-accident victims require mouth-to-mouth breathing.

restate key idea: an empty, tightly closed gallon jug will support a tired swimmer.  

restate key idea: first aid is to prevent accidents as well as assist in rescue.

explanation: the key idea needs to have the same topic as the key sentence (drowning and safety).

x=4, y=4

step-by-step explanation:

y=2x-4;

x+2y=12

we can use substitution since the first equation is solved for y

where ever you see y in the second equation, replace it with 2x-4

x + 2(2x-4) = 12

distribute the 2

x+4x-8 = 12

combine like terms

5x-8=12

add 8 to each side

5x-8+8=12+8

5x=20

divide by 5

5x/5 = 20/5

x =4

we still need to solve for y

y = 2x-4

we know x =4

y = 2(4) -4

y = 8-4

y=4