I need help with these questions plz help

1.A=bh/2

2A=bh

2A/b=h

  answer                   check

2.f(x)=21-6x               f(5)=21-6(5)            

 g(x)=2x/5-11            f(5)=21-30

21-6x=2x/5-11            f(5)=-9

21=32x/5-11              g(5)=2(5)/5-11

(5)32=32x/5(5)         g(5)= 10/5-11

160=32x                    g(5)=2-11

5=x                             g(5)=-9

3. f(7)=3(7)-7

   f(7)= 21-7

   f(7)= 14

Step-by-step explanation:

step-by-step explanation:

you divide the denominator by the numerator on both sides and if the quotients are equal then the fractions are equivalent