Can someone with problem 1 and/or 3?

#1

88+100+72+94=354 ---first 4 tests total

if he needs an average of 90, the total of 5 tests must = 90x5=450

450 - 354 = 96

his last test he needs to make 96 in order to average 90

#3

n, n+2, n+4 are 3 consecutive even numbers

4(n+n+2) = 2(n+4)

4(2n+2)=2(n+4)

8n+8 = 2n + 8

6n = 0

n = 0

n+2=0+2=2

n+4=0+4=4

3 consecutive even numbers are 0,2,4

double check

4 times sum of first and second equals twice the third

4(n+n+2) = 2(n+4)

4(0+0+2)=2(0+4)

4(2)=2(4)

8=8