Question

Kumar has twice as many $1 bills as $5 bills. If the total value of all of Kumar's $1 and $5 bills together is $35, how many $1 bills does Kumar have?

Answer 1

Let the number of $1 bills that Kumar has = x

Let the number of $5 bills that Kumar has = y

Given that Kumar has twice as many $1 bills as $5 bills

mathematically,

`x=2y\ldots\ldots\ldots\text{.}(1)`

Given also that the total value of all of Kumar's $1 and $5 bills together is $35

mathematically,

`\begin{gathered} x*\text{ \$1 + }y*\text{ \$5= \$35} \\ x+5y=35\ldots\ldots\ldots\text{.}(2) \end{gathered}`

Solve equations (1) and (2) simultaneously using substitution method

`\begin{gathered} x=2y\ldots\ldots\ldots\text{.}(1) \\ x+5y=35\ldots\ldots\ldots\text{.}(2) \\ \text{substitute }2y\text{ for }x\text{ in equation (2)} \\ 2y+5y=35 \\ 7y=35 \\ y=(35)/(7)=5 \\ To\text{ find x,} \\ \text{substitute 5 for y in equation (1)} \\ x=2(5)=10 \end{gathered}`

Therefore, the number of $1 bills that Kumar has is 10