0.19 for one cookie and 0.59 for one doughnut
x for how much one cookie costs and y for how much one doughnut costs
6x+4y=3.5
12x+5y=5.23
solve by substitution: (elimination would work too)
4y=3.5-6x
y=0.875-1.5x
12x+5(0.875-1.5x)=5.23
12x+4.375x-7.5x=5.23
4.5x=0.855
x=0.19
now use x to solve for y:
6(0.19)+4y=3.5
1.14+4y=3.5
2.36=4y
y=0.59
Check the work: 6(0.19)+4(0.59)=3.5
Add digit by digit, from the right, just like any number, except that if it adds to 2, then put a zero and carry one (instead of carrying when it adds to 10 or more).
Example: < means carry, decimal equivalent for checking
1011+1111
1 0 1 1 (8+2+1=11)
+ 1 1 1 1 (8+4+2+1=15)
---<---<----<----<----
1 1 0 1 0 (16+8+2=26)
Proceeding similarly,
a. 10101111+11011011 = 110001010 (394)
b. 10010111+11111111 = 110010110 (406)
c. 01110101+10101100 = 10010001 (289)
It’s green:b purple:d blue:c red:a because
Since the ratio of red to blue paint is 6 and 5. And 15 pints are blue you do 15 divided by 5 and it is 3. So you would do the same for red and it will be 18 so you do 18 plus 15 which is 33 pints in total