Let's solve your equation step-by-step.
x+78=90
Step 1: Subtract 78 from both sides.
x+78−78=90−78
x=12
Please put brainliest!
Answer:

Step-by-step explanation:
Since the question implies his truck travels at a constant distance per gallon, we can set up the following proportion to find how much father his truck can go.
Let
represent how much farther his truck can go, in kilometers:

Cross-multiplying, we get:

Across the largest side is going to be largest angle, and across the smallest side -smallest angle.
Sides:
BC = 9 < AB = 13 < CA = 17.
Angles that are across sides: A < C < B.
Answer is d- A C B.