Question 180229
Let the amount of $50 checks be f,
Then the amount of $20 checks is 2f
Let the amount of $100 checks be o


Therefore, 2f   +   f   +   o   =   10, or 3f   +   o   =   10
Then 2f(20) + f(50) + o(100)  =  370, or 40f + 50f + o(100) = 370, or 90f + 100o = 370


	 3f   +        o   =   10 ----------- (i)	
	      	90f    +   100o   =   370 --------- (ii)
        -90f    -    30o    =  - 300 -------- (iii) Multiply eq (i) by – 30:
			     70o    =   70    Add eq (iii) & eq (ii)
					         o    =   1   
Substituting 1 for o in eq (i), we get:  3f  +  1  =  10
						     3f   =   9   
						        f  =   3


Therefore, there are 2f, or 2(3) $20 checks, or 6 $20 checks  =  $120
					There are  f  or 3 $50 checks  =  $150  
					   There is  o  or 1 $100 check  =  $100 

Checking:
Altogether, there are 6 + 3 + 1 = 10 checks, and these checks add up to $120 + $150 + $100  =  $370.