
Add 7 to both sides

At the left hand side 7 will cancel 7
At the right hand side 7 will add up

Divide through by 2

simplify the fraction

Answer:
heart,lungs,oxygen i know i took a test like that before
+5 and -5 because you root 25 which gives you + 5 or - 5
It would be .2 not 2 because the smaller number is first
2 divided by 10 is .2
1 and 2 are vertical
3 and 4 are adjacent