I really hope this helps.
Answer:
23
Step-by-step explanation:
To find the Greatest Common Factor, or GCF, we need to factor the first 2 numbers and then find the greatest number that is both present in the prime factorization of both numbers.
253 = 1 * 11 * 23
345 = 3 * 5 * 23
Since 23 is both present in both numbers and is the greatest, the GCF of 253 and 345 is 23.
Answer:

Step-by-step explanation:
A proportion is an equation that defines that two ratios are equal. When the terms of a proportion are cross multiplied, the cross products are equal. Cross multiplication is the multiplication of the numerator of the first ratio by the denominator of the second ratio and the multiplication of the denominator of the first ratio by the numerator of the second ratio:

Therefore:
