x - first number
x + 18 - second number
x + (x + 18) = 36
x + x + 18 = 36
2x + 18 = 36 | - 18
2x = 18 | : 2
x = 9
First number: x = 9
Second number: x + 18 = 9 + 18 = 27
Those numbers are 9 and 27.
D.
24 is the distance Carlos biked
30 is the total distance
24:30 divided by 6
4:5
The first x coordinate is given by 0 and the second one is given as j. So the length of the base is j. (Sometimes in math they give letters rather than numbers. And since you know it is an isosceles then the other vertex should be at x-coordinate half j or j/2.