Answer:
x = 2
Step-by-step explanation:
This is an isosceles triangle, which means at least two sides are equal.
Set x + 3 equal to 3x-1 and solve for x.
x + 3 = 3x - 1 --- subtract x and add 1 to opposite sides.
4 = 2x --- divide 2 to each side.
2 = x
