Answer:
The expression 
has two variables x and y.
Step-by-step explanation:
<u>What is a variable?</u>
A variable is a letter, for instance 
or 
, that represents an unknown number.
Given the expression
The given expression has three terms which are x, 4y, and -9.
Here:
- The term 'x' is the unknown variable x.
- The term '4y' has a coefficient (the number next to a variable y) of 4.
- The term '-6' is a constant.
As we already know that a variable is a letter, for instance x or y, that represents an unknown number. In other words, the values of x, or y are unknown to us.
Thus, the expression has two variables x and y.
Let a = weight of large box in pounds
Let b = weight of small box in pounds
(1) 65a + 70b=4000
(2) a+b=60
Now we can simultaneously solve these equations.
a = 60 - b. Hence 65(60 - b) + 70b = 4000 So 3900 + 5b = 4000 and 100 = 5b hence b = 20.
SImilarly a = 40. Now we can verify too by putting in the calculated values.
Answer:
90
Step-by-step explanation:
9 x (3)2 + 9 first do the parenthesis
9 x 9 + 9 I am assuming the 2 was an exponent
81+9
90
Answer:
.
Step-by-step explanation:
Answer:
20
Step-by-step explanation:
Given
2x² - y ← substitute x = 3 and y = - 2 into the expression
= 2(3)² - (- 2)
= 2(9) + 2
= 18 + 2
= 20
