Forming Equations from Words Flashcards

All 3 cards in this deck

What are the steps to form and solve an equation from a 'think of a number' problem?

e.g. I multiply my number by 5, then add 7; the answer is 72

1. Call the number $x$ and write the operations: $5x + 7$
2. Set it equal to the answer: $5x + 7 = 72$
3. Solve: $5x = 65$, so $x = 13$

True or false? '5 less than $n$' is written as $5 - n$.

False. It is $n - 5$ — you start from $n$ and take 5 away.

What are the steps to form and solve two simultaneous equations from a cost problem?

e.g. 2 teas and 1 cake cost £5; 1 tea and 1 cake cost £3

1. Let $t$ = cost of a tea, $c$ = cost of a cake: $2t + c = 5$ and $t + c = 3$
2. Subtract to eliminate $c$: $t = 2$
3. Substitute back: $c = 1$, so a tea costs £2 and a cake costs £1