Answer:
ST = 13.75
Explanation:
The perimeter of a trapezium is calculated with the following formula:
P = a + b + c + d (a, b: bases, c, d: sides)
The perimeter of a rectangle is calculated with the following formula:
P= 2(a + b) (a: base, b: side)
we will write the following equation to find the length of ST
7x - 2 + 9x - 2 + 5x + 5x = 2(5x + 5 + 4x) first do the inside the parenthesis
2(9x + 5) = 18x + 10
Now,
7x - 2 + 9x - 2 + 5x + 5x = 18x + 10 add like terms on the left side of the equation
26x - 4 = 18x + 10 transfer like terms to the same side of the equation
26x - 18x = 10 + 4 add/subtract
8x = 14 divide both sides by 8
x = 1.75 replace x with this to calculate the lentgh of ST
5x + 5 = 5*(1.75) + 5 and ST = 13.75