Answer:
of iv
+
2
(
4
−
)
=
2
+
6
−
3
x+2({\color{#c92786}{4-x}})=2x+6-3x
x+2(4−x)=2x+6−3x
+
2
(
−
+
4
)
=
2
+
6
−
3
Step-by-step explanation:
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The first digit of a number can be 1-9. The 2nd and the 3rd digit can be 1-10. The last digit can be 0 or 5 ( 2 numbers ):
9 * 10 * 10 * 2 = 1,800
She could pick 1,800 different 4-digit numbers.
Add 1 to both sides:

In cases like this, we have to remember that a root is always positive, so we can square both sides only assuming that

Under this assumption, we square both sides and we have

The solutions to this equation are

But since we can only accept solutions greater than -1, we discard
and accept
.
In fact, we have

and

which is the only solution.
Percent of students brought their lunch from home is 100-24= 76%
So, total students are in the six grade is
190 x 100/76 = 250 students