Help me solve this ,would you?

[masrooranwer]

Comments

[mnine3]

The answer is 45

[missgee]

that would be 45

[yura81]

f(1,4)=5
f(2,5)=12
f(3,6)=21
f(5,8)=a
solve for a
=> f(a,b)=a * b+a
f(5,8)=5 * 8+5=45
answer: 45

[masrooranwer]

Make sense

[shrazi]

45 :D