Question

sometimes it is easier to use 2 variables when translating a word problem. then you must find a system of 2 equations to solve in order to find the solution to the problem. translate to a system of equation and solve.

roberta is 25 years older than her daughter, cindy. in 4 years, roberta will be twice as old as cindy. how old are they now?

Answer 1

r=c+25
r=2c+4

Answer 2

sorry r=2c-4

Answer 3

how does that equation work?

Answer 4

i just read the data...

Answer 5

let roberta's present age be x
and let cindy's present age be y
x=25+y
after four years,
roberts's age will be x+4 and cindy's age will be y+4
x+4=2(y+4)

Answer 6

now you can substitute x=25+y in x+4=2y+8

Answer 7

does y equal 2 ?

Answer 8

nope

Answer 9

25+y+4=2y+8
29-8=2y-y
y=21

Answer 10

so x=25+y
x=25+21
x=46

Answer 11

so the present age of roberta is 46 and cindy is 21

Answer 12

ohh now i get it

Answer 13

if robert's age = "x", & cindy's age ="y"
at present, x =25+y
and y = x - 25,
therefore, if y = 0, x = 25.

Answer 14

therefore in 4 yrs,
x = 2y+4
so, if x = y + 25 ---- (1)
x = 2y +4 ----(2)
substitute (1) in 2
y+25 = 2y+4
y = 21

therefore at present,
cindi = 21, and robert is 46

Answer 15

thank you