Answer:
10n - 7
Step-by-step explanation:
Choose a variable for the number
let "n" be the number
Take apart the statement in the question. Convert each part to algebraic form (numbers and symbols)
"Seven less than" -7
"the product of a number and 10" n*10 or 10n
Put the parts together
10n - 7
This is an expression, which means there is no equal sign. When there is an equal sign, it's an equation.
You cannot solve an expression, unless given the missing number.
The answer to that is 2.1
Part a: For variable X using z score you have (x-30)/10, replace X for this expression in (a), i mean Z=2+10((x-30)/10) = 2+x-30= put this in the way of z score = (x-18)/1, so the mean is 18 and standard deviation is 1.
Part b: Z=X+Y= (x-30)/10 + (x-20)/8 = solve adding fractions = (18x-440)/80 now divide all the numbers between 18 (because you need to show as z score way) = (x-24.4)/4.4, so the mean is 24.4 and standard deviation is 4.4.
For part c,do the same.
X = 2/3
Y= -1/2
Here you have solutions of two equation