explain 7/20-1/2
Let's evaluate: 720 -12
ⓘTo add fractions, put them over the same denominator, then add the numerators
7 -1×1020
ⓘMultiplications are done before additions and subtractions: -1×10 = -10
7 -1020
ⓘThe numerator and the denominator are computed before the division: 7 -10 = -3
▶Result:   -320
The approximate value of: -320 equals:
▷ -0.15