Answer:

Step-by-step explanation:
Factor each half of the expression separately:

Since both 4k² and 7 are being multiplied by (7k-6), we can combine them to get:

(35 + 47 + 42 + x) / 4 = 50
(124 + x) / 4 = 50....multiply both sides by 4, cancelling the 4 on the left side.
124 + x = 50 * 4
124 + x = 200
x = 200 - 124
x = 76 <===
As the volume of cuboid is given by,
l×b×h
as the dimensions are doubled,
l2×b2×h2
5×2×4×2×3×2
= 480 cm^3