Question

the sum of the digits of a two- digit number is 9. the sum of the number and its units digits is 74. find the number

Answer 1

call the digits of this 2 digit number t and u where t is the tens digit and u is the units digit.

then, from the information given to you, you have:

t + u = 9
10t + u + u = 74

solve this system of equations to find t and u

Answer 2

ok i see what you did

Answer 3

gr8!

Answer 4

@asnaseer do i solve each equation?

Answer 5

or do i solve the equations together

Answer 6

you need to solve the "system" of equations, i.e. solve them together. one way is to use the first equation to find an expression of t in terms of u, and substitute that into the second equation and solve for u. then find t from the first equation once you know u.

Answer 7

ok can u help me to solve it step by step please

Answer 8

why don't you make a start and I'll correct you if you start going wrong anywhere?

Answer 9

ok thanks

Answer 10

np :)

Answer 11

can u get me started....i have no idea how to start :(

Answer 12

ok, we have the following equation to solve:

t + u = 9
10t + u + u = 74

so first get an expression for t from the first equation - what do you get?

Answer 13

do i add t+10t???

Answer 14

look at this equation:

t + u = 9

rearrange it to get it into the form:
t = ...

Answer 15

9?

Answer 16

t + u = 9

we need to get u from the left-hand-side of this equation to the right-hand-side.
we do this by subtracting u from both sides of the equation.
what would we end up with after doing that?

Answer 17

so do i do (u-)t+(u-)u=9

Answer 18

ok - it looks like you first need to learn some of the fundamentals of algebra.

I would advise you to take a look through some of the short videos on this site: http://www.khanacademy.org/math/algebra/solving-linear-equations

they are very good and will help you get up to speed with this.