Change 2A to C, because 2A is 5 more than C, so 188 minus 5 is changed to C,

Similarly, replacing 2 B with c and subtracting 19 from 188 can also be replaced with c,

So: C+C +2 C = 188-5- 19.

4 C = 164，

c = 4 1a =(4 1+5)÷2 = 23 B = 94-4 1-23 = 30。