The value of x is 4. The steps to solving the equation are to use distributive property first so that the equation then looks like this: 10x+20=5x+40
Next you would combine like terms and then the equation would look like this: 5x+20=40
Then you would use the subtraction property of equality to subtract 20 from 40 so your equation will now look like this: 5x=20
Then you use the division property of equality to divide 20 by 5 to get x=4
It looks like the length of a and b should be the same. You can use the Pythagorean theorem (only works with right triangles):
a² + b² = c² (c is the hypotenuse or the longest side of the triangle, a and b are the other side lengths of the triangle)
a² + (4)² = (5)²
a² + 16 = 25
a² = 9
a = 3
a and b have a length of 3