Step-by-step explanation:
15t + 30 = 20t | -15t
30 = 5t
t = 30/5 = 6
20 + 5t = -6t + 86 | + 6t
20 + 11t = 86 | -20
11t = 66
t = 6
18t + 20 = 24t + 50 | -18t
20 = 6t + 50 | -50
-30 = 6t
t = -30/6 = -5
18t - 2 = 10t + 54 | -10t
8t - 2 = 54 | +2
8t = 56
t = 56/8 = 7
7t - 5 = 15t + 91 | -7t
-5 = 8t + 91 | -91
-96 = 8t
t = -96/8 = -12
The correct answer is number one
Do you have a picture? Normally this kind of problem features a graph with other points included. -1,6? -6,1? -11,6? -6,11?
Repetition is a guaranteed way to learn something. If it is a formula you need to learn, try doing flashcards and reading it over and over again until you can spell it without the flahcard. If it is something like factoring, just do a bunch of factoring problems until you get the feel of it.