Linear Equation
Question: A children’s gift store sells gift certificates in denominations of $3 and $5. The store sold ‘m’ $3 certificates and ‘n’ $5 certificates worth $93 on a Saturday afternoon. If ‘m’ and ‘n’ are natural numbers, how many different values can ‘m’ take?Question: A children’s gift store sells gift certificates in denominations of $3 and $5. The store sold ‘m’ $3 certificates and ‘n’ $5 certificates worth $93 on a Saturday afternoon. If ‘m’ and ‘n’ are natural numbers, how many different values can ‘m’ take?
Answer is 6.
someone please explain, what is the short cut to derive the 6 combinations for 93?
thanks
Hi Faiz,
The equation here is 3m + 5n = 93. This can also be written as 6m + 10n = 186.
Here we just use the units digit to solve. 186 has a units digit of 6, 10n will always give us a units digit 0, so 6m will have to give us a units digit 6. So the solutions will be m = 1, 6, 11, 16, 21 and 26.
Hope this helps!
CrackVerbal Academics Team