If two planes intersect then they intersect in exacly ___ lines

Δabc is reflected across line l to form δ alblcl, and a¯¯¯al¯¯¯¯ intersects line l at point d. which equation is not necessarily true?

In an improper fraction, is the numerator equal to, less than, or greater than the denominator

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.