Is there anyone who can give me a straightforward method, other than trial and error, for the following kind of problem set in today’s Grade 5 maths homework (and, no, they aren’t working with equations yet):-
“Mia goes to the supermarket and spends R20 on a gift for her mother. She then spends half of what she has left on a gift for her father. She buys a gift for R15-00 for her brother, and has R10-00 left over. How much did she start off with?”
I worked out the answer as being:
Mother 20-00 Given
Father 25-00 (1/2 of 70* minus 20)
Brother 15-00 Given
Left 10-00 Given
The only way I could do it was to work it back from guesstimates of the total cash*, adjusting up or down as necessary until it added up.