Solve for each system: 4a+b+3v = 31, 4a+b = 25, 5a=30

5a=30

5a/5=30/5

a=6

4a+b = 25

4(6)+b = 25

24+b = 25

24+b -24= 25-24

b=1

4a+b+3v = 31

4(6)+1+3v = 31

24+1+3v = 31

25+3v = 31

25+3v-25 = 31-25

3v=6

3v/3=6/3

v=2