Steve is presently 6 years younger than Lisa. If the sum of their ages is 40, how old is each?

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Answer 1 · 2018-04-10T23:50:58

I got:
Steve #17#
Lisa #23#

Let us call the ages of Steve #s# and Lisa #l#; we get:

#s=l-6#
and
#s+l=40#

substitute the first equation into the second for #s#:

#color(red)(l-6)+l=40#

#2l=46#

#l=46/2=23#

and so:

#s=23-6=17#

Answer 2 · 2018-04-10T23:55:32

Lisa is #23# and Steve is #17#.

Let's say that Steve's age is #s# and Lisa's age is #L#.

#s = L-6#

Since the sum of their ages is #40#, you could write

#40 = L + L - 6#

You could then simplify it to

#40 = 2L - 6#

Then like solving a two-step equation, first add the #6# on both sides. Now we have

#46 = 2L#

Finally, divide both sides by #2#. The result is

#23 = L#

This means that Lisa is #23# years old. To find Steve's age, do #L - 6# and replace #L# with #23#.

#23 - 6 = 17#

Thus, Lisa is #23# years old and Steve is #17# years old.