What value should come in place of the question mark (?) in the following question?

52x14+145018=1998÷?

If D and E are points on the sides AB and AC respectively of a triangle ABC such that DE||BC. If AD = x cm, DB = (x – 3) cm, AE = (x + 3) cm and EC= (x – 2) cm, then what is the value (in cm) of x?

If x + (1/x) = √13, then what is the value of x5 – (1/x5)?

What is the difference of the factors of the expression x2 + (1/x2) – 6?

If (x - 13)2 + (y - 4)2 = 0, then the value of y + xy - x ?

If the angle subtended by the radius of the circle and vertex B of the triangle ABC is 400. Then calculate the value of ∠BAC

What is the difference of the cube and square of the common root of (x2 – 8x + 15) = 0 and (y2 + 2y – 35) = 0?

Calculate the distance (in cm) of the chord from the centre of the circle, if the chord of length 48 cm is drawn in the circle of radius 25 cm.

If x2+1x2-6, then find the value of 2x(x-1)x3-x2-x+1