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3 years ago

How to subtractat a positive and negative rational number

Mathematics

1 answer:

Anna71 [15]3 years ago

5 0

Answer:

Step-by-step explanation:

Subtracting a number means adding the opposite.

The opposite of a number is the number you obtain by just changing the sign.

The opposite of 5 is -5. The opposite of 100 is -100. The opposite of -4.5 is 4.5. The opposite of 0 is 0. Zero is the only number that is equal to its opposite.

You need to subtract -45, so add the opposite of -45 which is 45.

30 - (-45) = 30 + 45 = 75

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ValentinkaMS [17]

Answer: 54

Step-by-step explanation:

3 times the square of -3 plus -5 times -3 plus 12

3 times 9 + 15 + 12

27+15+12=

7 0

3 years ago

A ferry departs from a port along the Sands River at 10:00 am. The ferry travels at a speed of 15 mph in still water and returns

jek_recluse [69]

Answer:

Speed of river's current = 5 mph

Step-by-step explanation:

Let 'd' be the distance covered

Let x be the speed of the rivers current

Speed upstream = 15-x

speed downstream = 15+x

Time = distance / speed

time upstream = $\frac{d}{15-x}$

time downstream = $\frac{d}{15+x}$

the ferry trip upstream takes twice as long as its return trip downstream

$\frac{d}{15-x}$ = $\frac{2d}{15+x}$

divide both sides by d

$\frac{1}{15-x}$ = $\frac{2}{15+x}$

cross multiply

$15+x= 2(15-x)$

$15+x= 30-2x$

Add 2x on both sideds

$15+3x= 30$

subtract 15 from both sides and divide by 3

$3x=15$

x=5

Speed of river's current = 5 mph

8 0

3 years ago

I have 6.5 yards of fabric and if the fabric costs $3.99 per yard how much will I spend

Masteriza [31]

Answer: You will spend 25.94$

Step-by-step explanation:

6.5 yards by 3.99 per yard = 6.5 times 3.99 = 25.935 witch rounds too 25.94$

4 0

2 years ago

Read 2 more answers