You have to plug in the numbers.
So first let's plug in 13. 7*13+8=99
Now 15. 7*15+8=113
Now 18. 7*18+8=134
Lastly 20. 7*20+8=148
The answer is 13.
I think it is, (1,1) I think that is it...
You divide it and the answer will be less
(-3i + 4)(3i + 4)
Use the FOIL method
multiply the Firsts: -3i * 3i = -9i² = because i² = -1 ⇒ -9i² = -9(-1) = 9
multiply the Outers: -3i * 4 = -12i
multiply the Inners: 4 * 3i = 12i
multiply the lasts: 4 * 4 = 12
9 - 12i + 12i + 12 = 21
The first one represents a proportional relationship