Answer:
Step-by-step explanation:
2/5 + 3/7 + 1/4 = 28/140 + 60/140 + 35/140 = 123/140
The attached image is the graph.
B) {x|x ∈ U and 2x is prime}
x is greater than 1.
the only even prime number is 2
2 times anything is even.
the minimum x value is 2. 2x is 4, therefore higher than the only even number
every value 2x will have a multiple of 2 so it will not be prime.
a is given to us so just plug a into the first equation:
b-3 - 3b =9
Add 3 to both sides:
b-3b=12
Combine like terms:
-2b=12
Divide by -2 to get b by itself:
b=-6
The only answer with b as -6 is the first one, (-9,-6)
8. first 12 bags for 54m^{2}
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54 ÷ 12 = 4.5
we know: 1 bag for 4.5m^2
36 ÷ 4.5 = 8
so 36m^2 we must use 8 bags
9.

x2 =5x2/8= 10/8 = 5/4 = 1.25
hope it helped you