Question

In the grid below, each number can be obtained through the sum of the two numbers connected directly below it. For instance, in the last row, the 5 is the sum of the two numbers below it, 2 and 3. Using the same method, all the numbers starting from the bottom row sums all the way up to the final square, 2x. Determine the value of x if the number in the topmost square is double unknown number in the bottom row.

Answer 1

x = -12.

Explanation:

Number in the square next to 5 = 3+x.

Number to the right of this one = x + 1

From left to right the umbers in the second row = 5 + 3 + x

and 3 + x + x + 1

= x + 8 and 2x + 4.

So x + 8 + 2x + 4 = 2x

so 3x + 12 = 2x

x + 12 = 0

x = -12.