The sum of two consecutive multiples of 10 is 210. find the smaller multiple.

The answer is:  " 100 " .

Explanation:


10x + 10(x+1) = 210 ;  Find "10x" ; 

10x + 10x + 10 = 210 ; 

20x + 10 = 210 ;

Subtract "10" from each side of the equation;
 
20x + 10 - 10 = 210 - 10 ;

20x = 200 ;

Divide EACH side of the equation by "20" ; to isolate "x" on one side of the equation; and to solve for "x" ;

20x / 20 = 200 / 20 ;

    x = 10

Solve for "10x";  the smaller multiple;

10x = 10 * x = 10 * 10 = 100 .

The answer is:  " 100 " .