Answer:
24 Letters and 4 Postcards
Step-by-step explanation:
We have to set up a system of equations, since we have two unknown variables. Lets say postcards is the variable "x" and letters is the variable "y".
Our first equation will be the money spent: 0.33x + 0.49y = 13.08, this comes from knowing that it costs 0.33 dollars to mail a postcard and 0.49 dollars to send a letter.
The second equation is the total sent: x + y =28.
Now we need to solve for a single variable, let's do y (or letters). If we subtract y from both sides we get: x = 28 - y.
We can plug that into our first equatino to get: 0.33(28 - y) + 0.49y = 13.08.
If we multiply things out we get: 9.24 - 0.33y + 0.49y = 13.08, and now we have like terms. 9.24 + 0.16y = 13.08.
Subtract 9.24 from both sides to get: 0.16y = 3.84
Divide both sides by 0.16 to get: y = 24.
Now we can plug this into x + y = 28 to see that x= 4.
You could make sure this is correct by solving for x instead of y and do the same process.
Hope this helps.
The last one, d, 2/3 < g < 2
A decimal point. Im guessing you meant to say tenths instead of tens
To convert a decimal (112) to base 8, divide by eight, keep the quotient and remainder. Repeat with the quotient.
112/8=14 R0
14/8=1 R6
1/8=0 R1
Read the remainders from bottom to top to get 160 (base 8) = 112 (decimal)
