Fill each bottom triangle, the first figure 1 triangle, the second figure 1+2 triangles, and the third figure 1+2+3 triangles. . . The tenth figure1+2+3+4+5+6+7+8+9+10 triangles (that is, 55 triangles).

The actual match is to subtract the number of matchsticks you add from the result of the above algorithm. The first picture is negative 1, the second picture is negative 2, and the third picture is negative 3. . . Subtract 10 from the tenth number.

So the answer is 55*3- 10= 155.

Formula: 3*( 1+n)n/2-n