Please can u show me step by step how to do this

Question

A triangle has a base 2x+1 and height 6x-3. What value of x would give an area of 240m2?

Answer 1

Area of a triangle = 1/2 * base * height

so 240 = 1/2 * (2x+1) * (6x-3)

480 = 12x^2 + 6x - 6x - 3

12x^2 = 483

x^2 = 483 /12

x = 6.34 (rounded to 2 decimal places)