Answer:
Number of facial muscles it takes to smile, S = 20
Step-by-step explanation:
Let
Number of facial muscles it takes to smile = S
Number of facial muscles it takes to frown, F = 46
This is 26 more muscles than it takes to smile
F = S + 26
46 = S + 26
Subtract 26 from both sides
46 - 26 = S + 26 - 26
20 = S
S = 20
The number of muscles it takes to smile is 20