Asmoothly operating engine depends on a. equal compression between cylinders. b. cylinder compression levels above 100 psi and within 70 psi of each other. c. compression levels below 100 psi on most cylinders. d. high compression on most cylinders.

A. equal compression between cylinders.

Explanation:

Equal compression between cylinders lead to uniform propelling of the shaft which in turn results into smooth motion of the shaft hence a smoothly operating engine.

In case of unequal compression, there shall be experienced unequal propelling which shall in turn result to rough engine  operation

if triangle abc is congruent to triangle def, their interior angles are congruent, because congruent parts of congruent triangles are congruent (cpctc).

that means ∠d is congruent to ∠a; ∠d is equal to 8x - 2.

interior angles of all triangles add to equal 180 degrees, so you can set the sum of these interior angle values equal to 180 and solve for x.

180 = (8x - 2) + 22 + 72

180 = 8x - 2 + 22 + 72

180 = 8x + 92

88 = 8x

11 = x

x = 11