Answer: 16 C 17 B i cant even read it if im right i want the brainliest
Step-by-step explanation:
Y=mx + c
first find 'm'
m=y2-y1/x2-x1
m= 21-15/7-3
m=6/4 or 3/2
then substitute values in from either points
y=mx+c
15=3/2 * 3 + c
15=9/2 + c
15-9/2=c
11/5=c
therefore the equation must be y=3/2 x 11.5
note: you substitute with either (3,15) or (7,21) you will get the same answer either way.

---Cross multiply
2x = 36
---Divide both sides by 2
x = 18
Hope this helps!