Final answer:
By setting the equal side lengths of an isosceles triangle to each other, we solve for x and find that x equals 9.
Step-by-step explanation:
In an isosceles triangle, two sides are equal in length. Since we know that MK = ML and their lengths are given as 7x - 15 and 10x - 42 respectively, we can set these two expressions equal to each other to find the value of x.
Setting the expressions equal, we get
7x - 15 = 10x - 42
We then solve for x by moving the variables to one side and the constants to the other:
7x - 10x = -42 + 15
-3x = -27
Therefore, x = 9.