One value: would be a single valued function, or just one answer.
Real numbers would be: natural numbers, whole numbers, integers, rational numbers (fractions and repeating or terminating decimals), and irrational numbers.
No solution: there is no answer to the question.
#13 would be 100%.
#15 would be $9.90.
#17 would be 408.
#19 would be 27840.
#21 would be 26.
Sorry for the late reply.
0.4x + 3.9 = 5.78
1. Subtraction property of equality:
Subtract 3.9 from both sides of the equal sign:
0.4x = 1.88
2. division property of equality:
Divide both sides of the equal sign by 0.4:
X = 4.7
20x+5y=120
10x+7.5y=80 multiply this one by 2
___________
20x+5y=120
20x+15y=160 subtract
___________
-10y=-40 divide both sides by -10
____________
y=4
20x+5(4)=120 plug 4 in for y in the first equation
20x+20=120 multiply
20x=100 subtract
x=5 divide to find x
five to the second power is 5x5 which is 25.
two to the fifth power is 2x2x2x2x2 which is 32.
