Sender: Angie Herbert Subject: algebra Hi My daughter is having problems with her algebra homework. She is a year 7 pupil at high school in the UK. She has been given homework on simplifying formulae and she doesn't understand how to do them. Here is an example of one of the questions : 9s+7t+5c+5s-3t can you help her to understand how to do these and perhaps me too. Thanks puzzled mum Angela Herbert Hi Angela, Simplifing this expression (some teachers may use the expression "collecting like terms") involves gathering all the s's, all the t's and all the c's. There are 9 s's and a further 5 s's so altogether 9+5=14 s's. Likewise there are 7 t's from which you remove 3 t's leaving you with 7-3=4 t's. To say it properly 9s + 7t + 5c + 5s - 3t = 9s + 5s + 7t - 3t + 5c = (9 + 5)s + (7 - 3)t + 5c = 14s + 4t + 5c Penny Here is another approach. Give meaning to the variables (for instance s: steaks, t: tomatoes, c: carrots  Rewrite the equation in this meaningful way: 9 steaks + 7 tomatoes + 5 carrots + 5 steaks - 3 tomatoes  Rewrite the above in a simpler way: 14 steaks + ...  Remove the meaning of the variables (put back s for steaks, t for tomatoes and c for carrots). Claude Go to Math Central