You plug in 2x + 4 into the y for the other equation (3x +y ) and solve for it
The cube root of 343 is 7.
One side has an area of 7*7 = 49 square cm
There are 6 sides to a cube
6 * 49 is the surface area = 294
There are <u><em>6.4008 </em></u><u><em /></u><em /><u><em>meters</em></u> in <u><em>21 feet</em></u>
If you need more help I will be glad to help:D
*~"AB84"~*