Zero pairs are basically 2 numbers that add up to zero like -1 +1 = 0 they cancel each other out. By assigning tiles to represent each number, you can cancel out the zero pairs and the remaining tiles will represent the sum or difference of the numbers.
The quantities in the proportion you give add to 16 pounds, of which 2 pounds are cement. That is, cement constitutes 1/8 of the total weight.
For each yard of concrete, 4000 lb/8 = 500 lb of cement are used.
For 12.5 yards of concrete, 12.5 * 500 = 6,250 pounds of cement will be used.
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"yard" in this case is shorthand for "cubic yard".
According to the rules of significant figures in counting the number of significant figures when dealing with the measurement, especially when it is scientifically measured, you must consider 2 zeros at the right of the period. For example, in 98.00 there are 4 significant figures
<span>1x + 2x = 15
3x = 15
3x/3 = 15/3
x = 5
Gemma = 1x, Zak = 2x therefore Gemma = 5 and Zak = 10</span>
