Solve 5*(16+15+14+13+12+11+10+9+8+7+6+5+4+3+2+1)=x

$$5 \times (16+15+14+13+12+11+10+9+8+7+6+5+4+3+2+1)=x$$

Solve for x

$$x=680$$

Steps for Solving Linear Equation

Add 16 and 15 to get 31.

$$5\left(31+14+13+12+11+10+9+8+7+6+5+4+3+2+1\right)=x$$

Add 31 and 14 to get 45.

$$5\left(45+13+12+11+10+9+8+7+6+5+4+3+2+1\right)=x$$

Add 45 and 13 to get 58.

$$5\left(58+12+11+10+9+8+7+6+5+4+3+2+1\right)=x$$

Add 58 and 12 to get 70.

$$5\left(70+11+10+9+8+7+6+5+4+3+2+1\right)=x$$

Add 70 and 11 to get 81.

$$5\left(81+10+9+8+7+6+5+4+3+2+1\right)=x$$

Add 81 and 10 to get 91.

$$5\left(91+9+8+7+6+5+4+3+2+1\right)=x$$

Add 91 and 9 to get 100.

$$5\left(100+8+7+6+5+4+3+2+1\right)=x$$

Add 100 and 8 to get 108.

$$5\left(108+7+6+5+4+3+2+1\right)=x$$

Add 108 and 7 to get 115.

$$5\left(115+6+5+4+3+2+1\right)=x$$

Add 115 and 6 to get 121.

$$5\left(121+5+4+3+2+1\right)=x$$

Add 121 and 5 to get 126.

$$5\left(126+4+3+2+1\right)=x$$

Add 126 and 4 to get 130.

$$5\left(130+3+2+1\right)=x$$

Add 130 and 3 to get 133.

$$5\left(133+2+1\right)=x$$

Add 133 and 2 to get 135.

$$5\left(135+1\right)=x$$

Add 135 and 1 to get 136.

$$5\times 136=x$$

Multiply 5 and 136 to get 680.

$$680=x$$

Swap sides so that all variable terms are on the left hand side.

$$x=680$$