It is simple
Step 1) substitute x = 5 into the equation
3x +4
3(5) + 4 gives you 3 times 5 + 4
The answer is 15 + 4 which is 19
Now substitute a and b into the equation 3(a) + 4(b) when the a = 6 and b = 5
Hereby 3(6) + 4(5)
3 * 6 = 18 and 4* 5 = 20
18 + 20 = 38
The answer is 38
Now finally
Substitute a and b Into the equation
3(3) + 4(6)
9+ 24 = 33
When u think of multiples...think of multiplication tables...
5 x 1 = 5
5 x 2 = 10
5 x 3 = 15
and so on.....so ur multiples of 5 are 5,10,15..and so on
so multiples of 5 starting at 75 would be.....75,80,85,90,95,100...and so on....not sure how far ur supposed to count to...
You have the slope and you have two points, so you can use the slope equation to find x.

So your answer is x = 8.