Answer:
30 red marbles
Step-by-step explanation:
If the ratio is 2 red marbles for every 5 blue marbles then you would add them together to find out how many marbles are in one group.
2+5=7
There are 7 marbles in each group.
Now we have to find out how many total groups there are by dividing the total amount of marbles by the amount in each group.
105÷7=15
There are 15 groups of 7 marbles.
Looking back at the ratio, we know that the 15 groups each have 2 red marbles and 5 blue marbles. So if there is 2 red marbles 15 times (2 marbles in 15 groups) we would multiply.
2×15=30
There are 30 red marbles.
I hope that makes sense.
Answer:
Step-by-step explanation:
U have to multiply 49 by 49 and then subtract 9
Answer:
It's the 4th one
Step-by-step explanation:
.................................
x² - 80 = 0
Add 80
to each side: x² = 80
Square root
each side: x = √80
Look it up: x = + 8.944... (rounded)
and
x = - 8.944... (rounded).
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Here's a cleaner solution:
x² - 80 = 0
Add 80
to each side: x² = 80
Square root
each side: x = √80
But 80 = 16 · 5
So √80 = √16 · √5
√16 = 4, so x = 4 √5
