Multiplication, addition, subtraction
Distribute on the left side
7.4a+22.2=3.2a+43.2
Subtract 3.2a from both sides
4.2a+22.2=43.2
Subtract 22.2 from both sides
4.2a=21
Divide both sides by 4.2
a=5
B. triangle ABC is isosceles. The angles add up 180 degrees.
I'm not sure what your statement is.
Is it x+y = 10?
Because if it is, the negation of this statement would simply be x+y<span>≠10, which stands for not equal. </span>
Let the first and smaller number be x. Since the second number is 5 times the first, the second number is 5x. We also know both of these numbers must add to 50; thus, we can create the following equation.

Combine like terms

Divide both sides by 6

This is the value of the first number. The number you're looking for isn't specified in the question description, so I'll just provide the value of the second number. The second number has to be 5 times the first.
Thus, we just multiply 5 to x.

That's the value of the second number.